gems, gemology, advanced gemology, gem testing, x-ray powder diffraction, analytical

Instruction in the various laboratory methods for investigating crystals has long been part of the mineralogy and geology curriculum at the Massachusetts Institute of Technology, encompassing both optical and x-ray techniques. While suitable texts exist for optical methods, there has been no adequate textbook on the x-ray powder method. To support lectures and prepare students for laboratory work, the authors initially wrote a set of notes on the theory and practice of this method, which eventually evolved into this book. The expanded format allowed for more detailed discussion and the inclusion of advanced material beyond what could be covered in a short course. The powder method is inherently simple yet widely valuable across science and industry, often used by individuals with no formal training in crystallography. This book is written with such users in mind, maintaining a fundamental approach while assuming only limited prior knowledge. It omits detailed coverage of general crystallography, x-ray generation, and equipment beyond powder cameras, as these are addressed in other sources. Detection methods using photographic film are emphasized, given their simplicity and permanence, despite the growing use of ionization-type detectors. The principles outlined apply regardless of detection technique, but film is expected to remain relevant in routine applications for the foreseeable future.